My son went through the same issues with ear infections and a high tolerance for pain. I wouldn't even realize he was sick until I touched him and realized he had a fever... then the doctor would say, "And he never touched his ears or pulled on them or anything?"
Once, we went in for something else and she noticed a cut over his eye. And she said, "How long has that been there? It needed stitches!" No tears, no stitches... those are my rules.
In Kindergarten, he broke his arm. Didn't cry. Didn't tell anyone. They didn't know until they took his coat off after recess and his arm was at the wrong angle!
There are real PROBLEMS when a child's pain tolerance is this high. Make SURE it gets noted in every doctor's file. I have seen that look on doctors' faces... when they don't know us and think I have ignored a problem that should have been causing a great deal of pain. I have to say, "He's autistic and one of his sensory problems is a very high tolerance for pain."
Also, it should be a good argument on your side for tubes... if you can't tell when Becca's ears hurt, you can't catch an ear infection in the early stages. That's why my son has some damage. Ear infections that are that bad do damage.